Crop harvesting machine

ABSTRACT

A crop harvesting machine including a longitudinal frame portion adapted at its forward end for attachment to a draft vehicle, a transverse frame portion fixed at its left end to the rearward end of the longitudinal portion, a pair of upright frame members fixed to opposite sides of the transverse frame portion, a pair of transversely spaced wheel arms connected to the transverse frame portion for vertical swinging movement and having groundengaging wheels rotatably mounted thereon, extensible and retractable means acting between the upright frame members and the wheel arms to vertically swing the latter and thereby raise and lower the frame relative to the ground, a header subframe carrying crop harvesting elements thereon, the header extending longitudinally above the transverse frame portion and between the upright frame members, upper and lower links mounting the header on the frame, the upper links extending between the header and the upper ends of the upright frame members and the lower links extending between the header and the wheel arms, and elongated springs acting between the transverse frame portion and the header to urge the latter upwardly relative to the former. In one embodiment, the springs extend between the upper ends of the upright frame members and the header, and in another embodiment, the springs extend between the upper links and the header.

United States Patent [1 1 Sawyer et al.

[ Mar. 19, 1974 CROP HARVESTING MACHINE [75] Inventors: Bobby GeneSawyer; J. Clark Fiekle, both of Wapello, Iowa [73] Assignee: Deere &Company, Moline, Ill.

[22] Filed: July 5, 1972 [21] Appl. No.: 268,976

Primary ExaminerLouis G. Mancene Assistant ExaminerJ. A. Oliff [57]ABSTRACT A crop harvesting machine including a longitudinal frameportion adapted at its forward end for attachment to a draft vehicle, atransverse frame portion fixed at its left end to the rearward end ofthe longitudinal portion, a pair of upright frame members fixed toopposite sides of the transverse frame portion, a pair of transverselyspaced wheel arms connected to the transverse frame portion for verticalswinging movement and having ground-engaging wheels rotatably mountedthereon, extensible and retractable means acting between the uprightframe members and the wheel arms to vertically swing the latter andthereby raise and lower the frame relative to the ground, a headersubframe carrying crop harvesting elements thereon, the header extendinglongitudinally above the transverse frame portion and between theupright frame members, upper and lower links mounting the header on theframe, the upper links extending between the header and the upper endsof the upright frame members and the lower links extending between theheader and the wheel arms, and elongated springs acting between thetransverse frame portion and the header to urge the latter upwardlyrelative to the former. In one embodiment, the springs extend betweenthe upper ends of the upright frame members and the header, and inanother embodiment, the springs extend between the upper links and theheader.

21 Claims, 9 Drawing Figures 'PATENTEDHAR 19 I974 SHEEI 1 [1F 7 PATENIEDMAR 1919?:

SHEET 2 BF 7 PAIENIEUMAR 1 9 m4 StitET 5 BF 7 CROP HARVESTING MACHINEBACKGROUND OF THE INVENTION The present invention relates generally tocrop harvesting machines and more particularly to a frame structure andheader suspension mechanism for a crop harvesting machine of themower-conditioner type.

A conventional pull-type mower-conditioner includes an L-shaped mainframe adapted at its forward end for attachment to the drawbar of atractor and having .a transversely spaced pair of ground-engaging wheelsmounted on its transverse rear portion and adapted to support the framefor movement through a field. Suspended from the transverse frameportion is a subframe or header having a transverse cutter bar disposedalong its lower leading edge and adapted to cut a swath of crop materialas the machine is advanced forwardly, an upper and lower pair of cropconditioning rolls mounted upwardly and rearwardly from the cutter bar,the conditioning rollsbeing operative to condition the stems of the cutcrop material and discharge the crop along a curved path extendingrearwardly from the rolls and thence downwardly to the ground, and aharvesting reel for directing the standing crop into the cutter bar andtransferring the cut crop upwardly and rearwardly from the cutter bar tothe conditioning rolls. Adjustable deflector means are included at therear of the header for selectively deflecting the swath of crop materialdischarged from the conditioning rolls either into a relatively wideswath or a relatively narrow windrow.

Various frame configurations and header suspension mechanisms have beenemployed on machines of this type in the past, examples of which aredisclosed in U.S. Pat. Nos. 3,474,601 issued Oct. 28, 1969 to Burroughet al., 3,517,491 issued June 30, 1970 to Lausch et al. and 3,550,363issued Dec. 29, 1970 to Halls et al.

SUMMARY OF THE INVENTION It is a primary object of the invention toprovide a crop harvesting machine of the mower-conditioner type havingan improved frame construction and header suspension means.

It is a more particular object of the invention to provide such amachine having improved header flotation characteristics and thusimproved cutter bar gauging characteristics.

It is a further object ofthe invention to provide such a machine havinga rigid, yet simple and economical frame construction.

It is another object of the invention to provide such a machine having aheader suspension linkage including stop means for limiting the relativeupward movement of the header when the frame is raised to a transportposition. 7

In pursuance of these and other objects, the crop harvesting machine ofthe invention comprises, generally, a longitudinal frame portion adaptedat its forward end for attachment to a draft vehicle, a transverse frameportion fixed at its left end to the rearward end of the longitudinalportion, a pair of upright frame members fixed to opposite sides of thetransverse frame portion, a pair of transversely spaced wheel armsconnected to the transverse frame portion for vertical swinging movementand having ground-engaging wheels rotatably mounted thereon, extensibleand retractable means acting between the upright frame members and thewheel arms to vertically swing the latter and thereby raise and lowerthe frame relative to the ground, a header subframe carrying cropharvesting elements thereon, the header extending longitudinally abovethe transverse frame portion and between the upright frame members,upper and lower links mounting the header on the frame, the upper linksextending between the header and the upper ends of the upright framemembers and the lower links extending between the header and the wheelarms, and elongated, vertically extending springs acting between thetransverse frame portion and the header to urge the latter upwardlyrelative to the former. In one embodiment of the invention, the springsextend between the upper ends of the upright frame members and theheader, while in another embodiment, the springs extend between theupper links and the header. In both embodiments, the springs act throughbell cranks on the header to bias one of the crop conditioning rollsmounted thereon toward its cooperating roll.

The lower links mounting the header to the frame are pivotally connectedat their rearward ends-to intermediate portions of the wheel armsandextend forwardly beneath the transverse frame portion and arepivotally connected at their forward ends to the header. During normaloperation, the upper side of the lower links are thus engageable withthe lower side of the transverse frame portion to limit the upwardmovement of the header relative to the frame. Downward movement of theheader relative to the transverse frame portion is limited by the lowerside of the former engaging the upper side of the latter. When the wheel.arms are swung downwardly to raise the machine for transport, the rearpivotal connections of the lower links on the wheel arms are swungdownwardly and forwardly, thereby altering the geometry of the headersuspension linkage. As a result, the lower links engage a stop on theheader to limit the upward movement of the header relative to the lowerlinks when the machine is in its transport position.

BRIEF DESCRIPTION OF THE DRAWINGS dance with the principles of theinvention, showing the machine in its raised, transport position;

FIG. 2 is a side elevational view similar to FIG. 1 but showing themachine in its lowered, operating position;

FIG. 3 is an enlarged, fragmentary left side elevational view of themachine with portions removed for the sake of clarity, showing the framestructure and header suspension mechanism in greater detail, the headerbeing shown in its normal operating position;

FIG. 4 is a side elevational view similar to FIG. 3 but showing theheader raised to its maximum height position relative to the frame;

FIG. 5 is a plan view of the machine;

FIG. 6 is a fragmentary right side elevational view of the machine;

FIG. 7 is a rear elevational view of the machine on the same scale asFIG. 5;

FIG. 8 is a fragmentary left side elevational view of the machineshowing a modified header suspension spring mounting; and

FIG. 9 is a fragmentary plan view of the modified spring mounting ofFIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the ensuing description,rightand left-hand reference is determined by facing the direction oftravel of the machine.

Referring now to the drawings, the preferred embodiment of the inventionincludes a generally L-shaped main frame structure comprised of alongitudinal draft portion 10 on the left side of the machine and atransverse portion 11 connected at its left end to the rear of the draftportion. The longitudinal portion consists of a tongue member 12 adaptedat its forward end for attachment to the drawbar 14 of a draft vehiclein the form of a conventional agricultural tractor shown partially at16, and pivotally mounted at its rear end by means of a generallyvertical pin 18 between the upper and lower sides of a box frame section20. The section 20 has an arcuate leading edge member 22 provided with aplurality of spaced apertures into which a pin 24 carried by the tongue12 is releasably positionable to secure the tongue 12 in various angularpositions of adjustment relative to the section 20. In FIG. 5, thetongue 12 is illustrated in its extreme left position. To narrow thetractor-machine combination for transport purposes, the tongue would beswung to and secured in its extreme right position.

Fixed at its left end to the right rear portion of the section 20 is atransverse beam 26 having a transversely spaced pair of upwardly andrearwardly extending upright frame members 28 and 30 fixed to its rightand left ends, respectively. A right and left pair of relatively wide,small diameter wheels 32 and 34, respectively, support the main framestructure relative to the ground, the wheels 32 and 34 being mounted onthe transverse beam 26 just inwardly of the members 28 and 30,respectively. Each wheel is rotatably supported on a transverse axle 36extending between the rear ends of an outer wheel supporting arm 38 andan inner wheel supporting arm 40, the arms 38 and 40 beinginterconnected at their forward ends by means ofa tubular member 42which is rotatably received in a bracket 44 fixed to the lower rearcorner of the transverse beam 26. The upright frame members 28 and 30are each composed of a rearwardly opening, U-shaped channel, anddisposed between the walls of each member is an extensible andretractable hydraulic cylinder 46 for raising and lowering the wheelsrelative to the frame and thereby raising and lowering the framerelative to the ground. The upper end of each cylinder 46 is pivotallyconnected at 48 between the walls of its respective frame member, andthe lower end thereof is pivotally connected to the extreme outer end ofthe adjacent wheel axle 36. FIG. 1 illustrates the hydraulic cylinders46 in their extended positions and the machine in its raised transportposition, while FIG. 2 illustrates the hydraulic cylinders in theirretracted positions and the machine in its lowered operating position.The cylinders 46 are connected by conventional means (not shown) with ahydraulic fluid source on the tractor to extend and retract at the samerate of speed, so that the machine is maintained in a transversely levelcondition as it is raised and lowered.

Suspended from the transverse portion 26 of the main frame 10 is asubframe or header 50 which carries the various harvesting elements ofthe machine. The header is formed of right and left side panels 52 and54, respectively, interconnected at their forward ends by a transversecrop-engaging bar 56, at their upper rear ends by means of a transverseupper beam member 58, and at their lower center portions by a transverselower beam member 60 and a transverse arcuate ramp 62. Fixed to andextending rearwardly from the side panels 52 and 54 and the upper beam58 is a downwardly opening crop deflector hood structure designatedgenerally by the numeral 64 and formed by a generally horizontal topwall 66, a right and left pair of rearwardly converging, generallyvertical side walls 68 and 70, respectively, fixed to and extendingdownwardly from opposite sides of the top wall 66, and a downwardly andrearwardly inclined rear wall 72 interconnecting the rear edges of thetop wall 66 and side walls 68 and 70. As is apparent from the drawings,the hood structure 64 is positioned in overlying relation to the groundwheels 32 and 34, the latter being located directly beneath the top wall66 and between the side walls 68 and 70.

As described in detail in copending application Ser. No. 268,562, thesmall diameter ground wheels 32 and 34 are located rearwardly of andwithin the transverse extent of the mowing apparatus and conditioningrolls so that the crop discharged rearwardly from the rolls passesdirectly over the wheels before it falls to the ground. Also describedin this copending application, though forming no part of the presentinvention, are crop deflector means which may be carried by the hoodstructure 64, the deflector means being adjustable to form thedischarged crop in either a relatively wide swath or a relatively narrowwindrow.

The subframe or header 50 extends longitudinally between the uprightframe members 28 and 30 and is suspended from the transverse portion ofthe main frame 10 by means of a mechanism which permits the header tofloat relative to the main frame and thereby closely follow the contourof the ground and raise to clear obstructions which are encountered.This mechanism comprises, generally, upper and lower pairs oftransversely spaced links which interconnect the header 50 and mainframe, and tension spring means acting between the frame and the headerto urge the latter upwardly relative to the former. Two separateembodiments of the suspension mechanism are illustrated in the drawings.Referring first to FIGS. 1-7 of the drawings, the mechanism illustratedtherein includes a pair of mirror image upper link members formed ofidentical inner and outer, transversely spaced vertical plates 92interconnected along their upper and rear edges by means of a transverseplate 94, the latter including a portion substantially overhanging theouter plate 92. The rear portions of the vertical plates 92 of the leftlink 90 extend on opposite sides of the upper end of the member 30 whichis fixed to and extends upwardly and rearwardly from the transverse beam26. A pin 96 extends through aligned apertures in the plates 92 andmember 30 to pivotally connect the left link 90 to the main frame. Inlike manner, the vertical plates 92 of the right link 90 extend onopposite sides of the upper end of the member 28 and are pivotallyconnected thereto. The forward portions of the plates 92 of the leftlink 90 are pinned at 98 to the left side panel 54 of the header- 50,and, similarly, the forward portions of the plates 92 of the right link90 are pinned to the right side panel 52 of the header. The suspensionmechanism illustrated in FIGS. 1-7 further includes a pair of lower linkmembers 100, the rear ends of which are pivotally connected at 102 tothe center portion of the outer wheel arms 38, and the front ends ofwhich are pivotally connected at 104 to brackets 106 fixed to the rearwall of the transverse header beam 60.

A pair of fore-and-aft float springs 108 and 110 respectively, actbetween the left upper link 90 and the header to resiliently support theleft side of the header relative to the main frame, the springs beinganchored attheir upper ends to the overhanging portion of the transverseplate 94. The lower end of the rear spring 110 is anchored to a bracket112 which is fixed to and extends rearwardly from the left side panel 54of the header, while the lower end of the from spring 108 is anchored toone arm of a bell crank 114 pivotally mounted at 116 on the side panel54. As will subse quently appear, the spring 108 acts through the bellcrank 1 14 to provide a biasing force for the crop conditioning rolls onthe header. Since the weight of the right side of the header 50 issomewhat less than that of the left side, only a single float spring 118is employed to support this side of the header. The spring 118 isanchored at its upper end to the overhanging portion of the plate 94 ofthe right link 90 and at its lower end to a bell crank 114 pivotallymounted on the right header side panel 52.

It will be apparent that, with the machine in its lowered, operatingposition, the upper and lower links of the suspension mechanism act asparallel link means to maintain the header in a constant orientationrelative to the ground as it floats to follow the ground contour. FIG. 3illustrates the header in its normal operating position relative to theframe. Should the leading edge of the header strike an obstruction, theheader is free to move upwardly relative to the frame to clear theobstruction as shown in FIG. 4. The maximum height position of theheader relative to the transverse frame member 26, as shown in thisfigure, is defined by the point at which the upper side of the lowerlink 100 contacts the lower side of the member 26. Similarly, theminimum height position of the header relative to the transverse framemember 26 is defined by the point at which the lower side portion 120 ofthe header contacts the upper side of the member 26. When the machine israised to its transport position of FIG. 1, the lower links 100 are nolonger parallel to the upper links 90, since the pins 102 connecting therear ends of the links 100 to the wheel arms 38 are moved downwardly andforwardly relative to the main frame. The forward movement of the pin102 is transmitted to the header transverse beam via the link 100,causing the header to swing upwardly relative to the main frame foradditional transport height. Still referring to FIG. 1, it will be seenthat when the machine is raised the leading edges of the lower links 100contact the rear wall of the header transverse beam 60, the beam 60thereby acting as a stop member to limit the upward flotation of theheader relative to the lower links for transport purposes, and thus toincrease the transport stability of the machine.

A slightly modified header suspension mechanism is illustrated in FIGS.8 and 9, wherein the same reference numerals are used as in FIGS. 1-7 toindicate elements common to the two embodiments. Although only the leftside of the machine is illustrated in these figures, the right side issubstantially identical to the left side with the exception of thosechanges describedv below. The embodiment illustrated in FIGS. 8 and 9 issimilar to that already described in that it employs generally the sameframe configuration, with the exception that the upright member 30 isshaped somewhat differ ently and is disposed at a slightly greater anglefrom a vertical line. The wheel arm 38 and wheel 34 are the same, as isthe hydraulic cylinder 46 employed to swing the arm 38 about its pivotalconnection with the transverse frame portion, and the lower linkinterconnecting the wheel arm 38 with the header. The principaldifferences between the two embodiments reside in the upper linkconstruction and float spring mounting. The embodiment of FIGS. 8 and 9includes an upper link. 122, the forward end of the link being pivotallyconnected to the left header side panel 54 by a pin 124, and the rearend thereof being pivotally connected by means of a pin 126 to a bracket128 fixed to the front side of the upright frame member 30. Despite thedifferent shapes of the links 90 and 122, it will be apparent from acomparison of FIGS. 3 and 8 that the locations of the pivotalconnections of the links to the header and upright frame member aresubstantially the same in both embodiments and that the geometry of theheader suspension linkage is thus unchanged.

In the embodiment illustrated in FIGS. 8 and 9, however, the floatsprings which act to urge the header upwardly relative to the frame aremounted at their upper ends not to the upper link but rather directly tothe upper end of the frame member 30. A channel member 130 is fixed tothe upper end of the frame member 30 and extends transversely outwardlytherefrom. An inner end outer pair of float springs 132 and 134,respectively, are anchored at their upper ends to the channel member130, the inner spring 132 being connected at its lower end to the bellcrank 114, and the outer spring 134 being connected at its lower end toa bracket 136 which is fixed to and extends outwardly and rearwardlyfrom the left side panel 54 of the header. Although not shown in thedrawings, the right side of a machine constructed in accordance with theembodiment illustrated in FIGS. 8 and 9 includes only a single springinterconnecting a bracket extending outwardly from the upper end of theupright frame member 28 and one arm of the right bell crank 114. Sincethe geometry of the suspension linkage comprising this embodiment issubstantially the same as that comprising the embodiment of FIGS. 1-7,it will be appreciated that the description of the operation of thefirst embodiment as it relates to the manner in which vertical movementof the header relative to the transverse frame portion 26 is limited,and also to the transport configuration and characteristics of themachine, apply equally to the embodiment of FIGS. 8 and 9.

The harvesting components carried by the header include a conventional,reciprocating-type mowing apparatus extending transversely across thefront side of the lower transverse beam 60, the apparatus beingoperative to mow a swath of crop material as the machine is advancedforwardly through a field; an upper and lower pair of intermeshing cropconditioning rolls 138 and 140, respectively, the rolls being operativeto condition the mowed crop by cracking the stems thereof to facilitatethe escape of moisture; and a conventional, retractable finger-type reel142 mounted above the mowing apparatus and forwardly of the conditioningrolls to direct standing crop into the mower and advance the mowed cropup the arcuate ramp 62 from the mower to the conditioning rolls. Themowing apparatus is of a type well known in the art and comprises aplurality of transversely spaced guards 144 mounted along the front sideof the beam 60, and an elongated sickle bar 146 reciprocabletransversely through slots formed in the guards. Reciprocating motion isproduced for driving the sickle bar by means of a conventional wobbledrive mechanism contained within a housing 148 mounted on the extremeleft end of the beam 60, the mechanism having a rotary input shaft witha drive sheave 150 mounted thereon.

As is clear from FIGS. and 7 of the drawings, the crop conditioningrolls 138 and 140 extend the full width of the header 50, between theside panels 52 and 54. The lower crop conditioning roll 140 is supportedon a shaft 152 which, in turn, is rotatably mounted at opposite ends onthe header side panels 52 and 54. The upper roll 138 is supported on ashaft 154, the shaft 154 being supported at its ends on parallel arms156 pivoted at 158 to the header side panels. It will be seenthat themounting for the upper roll permits the latter to move toward and awayfrom the fixed position lower roll, along an arcuate path about thepivot 158. In the embodiment of the invention illustrated in FIGS. 1-7of the drawings, a downward biasing force is exerted on the ends of theupper roll by means of the float springs 108 and 118, each of which isanchored at its lower end to one of the arms of a bell crank 114. In theembodiment illustrated in FIGS. 8 and 9, float springs 132 bias theupper roll toward the lower roll. In both embodiments, the other arm ofeach of the bell cranks is connected by means of a vertical connectinglink 160 to one of the parallel arms 156 supporting the upper roll shaft154. It will thus be apparent that the float springs serve the dualfunction of providing flotation for the header while simultaneouslybiasing the upper roll against the lower roll. Should a rock or otherobject be introduced between the rolls along with the crop material, thesprings will stretch to allow the upper roll to move away from the lowerroll a distance sufficient to pass the object without damaging the rollsor their supporting structure.

The reel 142, shown only schematically in the drawings, is also ofconventional design and includes a pair of circular end panels 162 and164 interconnected by a plurality of transverse pipe members 166. Acentral shaft .168 also interconnects the end panels 162 and 164 and isrotatably supported at its ends in the header end panels 52 and 54. Anadjusting mechanism indicated generally by the numeral 170 is providedon the end panels at each end of the shaft 168 to permit adjustment ofthe reel height relative to the mowing apparatus. Conventionally, thereel pipe members 166 have a series of fingers mounted thereon whichextend and retract as the reel rotates. The action of the fingers iscontrolled by a cam 172 mounted on the inner wall of the left side panel52, the cam being engaged by cam followers (not shown), one of which isprovided for the set of fingers mounted on each of the reel pipe members166.

Power for driving the harvesting components on the header is supplied bythe power take-off shaft on the rear of the tractor 16. A short,telescoping shaft 174 connects the tractor power take-off shaft to thefront end of a main, longitudinal drive shaft 176 concealed in FIGS. 1and 2 of the drawings by a shield 178. The rear end of the shaft 176 isconnected by a universal joint 180 to the input shaft of a gear case 182mounted on the outer side of the left header side panel 52. Theharvesting component drive apparatus, including the manner in which thegear case 182 is mounted on the header side panel 52, is the subject ofcopending application Ser. No. 266,210. The rear portion of the gearcase 182 is pivotally connected by means of a bolt 184 to a bracket 186fixed to the panel 52. An additional pair of bolts 188, only one ofwhich is visible in the drawings, secures the forward portion of thegear case 182 to the bracket 186, the bolts 188 being received inarcuate slots in the bracket 186 so that the gear case can be swungabout the bolt 184 to various positions of adjustment when the bolts 188are loosened. The gear case adjustment provided in this manner is forthe purpose of maintaining proper tension in a belt 190 which drivinglyconnects an output sheave 192 on the front portion of the gear case withthe sheave 150 on the input shaft of the wobble drive mechanism for themowing apparatus. When the tension in this belt has decreased as aresult of wear, the gear case can be adjusted upwardly to restore propertension therein.

The gear case 182 further includes a pair of oppositely rotating outputshafts 194 and 196 for driving the upper and lower conditioning rolls,respectively. A short, telescoping power shaft 198 is connected at itsouter end through a universal joint 200 to the gear case output shaft194 and at its inner end through a universal joint 202 to the upper rollshaft 154. A second telescoping power shaft 204 is connected at itsouter end through a universal joint 206 to the gear case output shaft196 and at its inner end through a universal joint 208 to the lower rollshaft 152. The flexible connections between the gear case output shafts194 and 196 and the conditioning roll shafts 154 and 152, respectively,provide for misalignment between these shafts which occurs, in the caseof both sets of shafts, as the position of the gear case is changed totension the mowing apparatus drive belt 190, and, in the case of theupper set of shafts, when the upper roll moves away from the lower rollto pass an obstruction between the rolls.

The reel 142, as shown best in FIG. 6, is driven from the right side ofthe upper conditioning roll shaft 154. A chain 210 drivingly connects asprocket 212 on the extreme right end of the upper roll shaft 154 with asprocket 214 on a jackshaft 216 aligned with the pivot 158 of the upperroll support arm 156. Also mounted on and rotatable with the jackshaft216 is a sheave 218 which is drivingly connected by means of a belt 220to a sheave 222 on the right end of the reel shaft 168. An idler sheave224, adjustably mounted on a bracket 226 on the right header side panel52, is operative to maintain proper tension in the reel drive belt 220.

We claim:

1. A crop harvesting machine comprising: a longitudinal frame portionadapted at its forward end for attachment to a draft vehicle; atransverse frame portion rigidly fixed at one end to the rearward end ofsaid longitudinal frame portion; a pair of transversely spaced uprightframe members rigidly fixed at their lower ends to said transverse frameportion; a pair of longitudinally extending, transversely spaced wheelarm means pivotally connected at their forward ends to said transverseframe portion for vertical swinging movement, each of said wheel armmeans having a ground-engaging wheel rotatably supported on its rearwardend; extensible and retractable means interconnecting said upright framemembers and said wheel arm means for vertically swinging the latter andthereby raising and lowering the frame portions relative to the ground;a header subframe carrying harvesting elements thereon, said headerbeing disposed generally above and forwardly of said transverse frameportion and including a portion extending rearwardly between saiduprightframe members; lower, longitudinally extending link meansinterconnecting said wheel arm means and a lower portion of said header;upper, longitudinally extending link means interconnecting the upper endportions of said upright frame members and an upper portion of saidheader; and resilient means acting between said transverse frame portionand said header for urging the latter upwardly relative to the former.

2. The invention defined in claim 1 wherein said resilient meanscomprises spring means interconnecting said upper link means and saidheader.

3. The invention defined in claim 1 wherein said resilient meanscomprises spring means interconnecting the upper end portions of saidupright frame members and said header.

4. The invention defined in claim 1 including stop means on said headerengageable with one of said link means to limit the relative movementbetween said one link means and said header as the wheel arm means areswung downwardly to raise the frame portions relative to the ground.

5. The invention defined in claim 4 wherein said stop means areengageable with said lower link means to limit the upward movement ofthe header relative to the lower link means as the wheel arm means areswung downwardly.

6. The invention defined in claim 1 wherein said lower link means-extendbeneath the transverse frame portion.

7. The invention defined in claim 6 wherein the upper side of said lowerlink means is engageable with the lower side of said transverse frameportion to limit the upward movement of said header relative to saidtransverse frame portion.

8. The invention defined in claim 1 wherein the lower side of saidheader is engageable with the upper side of said transverse frameportion to limit the downward movement of said header relative to saidtransverse frame portion.

9. The invention defined in claim 1 including an upper and lower pair ofcooperating, crop conditioning rolls mounted on said header, one of saidrolls being mounted on said header for movement toward and away from theother of said rolls, and wherein said resilient means acts between saidtransverse frame portion and said one conditioning roll tosimultaneously urge the header upwardly relative to the transverse frameportion and urge said one conditioning roll toward said otherconditioning roll.

10. The invention defined in claim 9 including arm means mounting theupper of said crop conditioning rolls on said header for verticalswinging movement toward and away from the lower of said rolls, bellcrank means mounted on said header, and link means interconnecting onearm of said bell crank means with said upper roll mounting arm means;and wherein said resilient means acts between the other arm of said bellcrank means and said transverse frame portion.

11. The invention defined in claim 10 wherein said resilient meanscomprises spring means interconnecting the other arm of said bell crankmeans and said upper link means.

12. The invention defined in claim 10 wherein said resilient meanscomprises spring means interconnecting the other arm of said bell crankmeans and the upper end portions of said upright frame members.

13. The invention defined in claim 1 wherein said ground-engaging wheelsare disposed inwardly of said upright frame members and beneath theportion of said header extending rearwardly between said upright framemembers.

14. A pull-type crop harvesting machine comprising: a longitudinal frameportion adapted at its forward end for attachment to a draft vehicle; atransverse frame portion rigidly fixed at its left end to the rearwardend of said longitudinal frame portion; right and left, transverselyspaced upright frame members rigidly fixed at their lower ends to therespective end portions of the transverse frame portion; right and left,transversely spaced wheel arms pivotally connected to the transverseframe portion adjacent to the lower ends of the respective upright framemembers, each of said wheel arms extending rearwardly from its pivotalconnection with the transverse frame portion and having a groundengagingwheel rotatably supported on its rearward end; right and left,extensible and retractable means interconnecting the respective uprightframe member and wheel arm to vertically swing the latter and therebyraise and lower the frame portions relative to the ground; a headersubframe carrying harvesting elements thereon, said header beingdisposed generally above and forwardly of said transverse frame portionand including a portion extending rearwardly between said upright framemembers; right and left, longitudinally extending lower links pivotallyconnected at their rearward ends to intermediate portions of therespective wheel arms, said lower links extending forwardly therefrombeneath said transverse frame portion and being pivotally connected attheir forward ends to lower portions of said header; right and left,longitudinally extending upper links pivotally connected at theirrearward ends to the upper ends of the respective upright frame membersand at their forward ends to upper portions of said header; and rightand left, vertically extending spring means connected at their upperends to the upper ends of the respective upright frame members and attheir lower ends to the header.

15. The invention defined in claim 14 wherein said ground-engagingwheels are disposed inwardly from said upright frame members and saidspring means are disposed outwardly from said upright frame members.

16. The invention defined in claim 14 wherein said upright frame membersare formed of rearwardly opening, U-shaped channels, and wherein saidextensible and retractable means comprise hydraulic cylinders disposedbetween the walls of said channels.

17. A pull-type crop harvesting machine comprising: a longitudinal frameportion adapted at its forward end for attachment to a draft vehicle; atransverse frame portion rigidly fixed at its left end to the rearwardend of said longitudinal frame portion; right and left, transverselyspaced upright frame members rigidly fixed at their lower ends to therespective end portions of the transverse frame portion; right and left,transversely spaced wheel arms pivotally connected to the transverseframe portion adjacent to the lower ends of the respective upright framemembers, each of said wheel arms extending rearwardly from its pivotalconnection with the transverse frame portion and having a groundengagingwheel rotatably supported on its rearward end; right and left,extensible and retractable means interconnecting the respective uprightframe member and wheel arm to vertically swing the latter and therebyraise and lower the frame portions relative to the ground; a headersubframe carrying harvesting elements thereon, said header beingdisposed generally above and forwardly of said transverse frame portionand including a portion extending rearwardly between said upright framemembers; right and left, longitudinally extending lower links pivotallyconnected at their rearward ends to intermediate portions of therespective wheel arms, said lower links extending forwardly therefrombeneath said transverse frame portion and being pivotally connected attheir. forward ends to lower portions of said header; right and left,longitudinally extending upper links pivotally connected at theirrearward ends to the upper ends of the respective upright frame membersand at their forward ends to upper portions of said header; and rightand left, vertically extending spring means connected at their upperends to intermediate portions of the respective upper links and at theirlower ends to the header.

18. A harvesting machine comprising: a mobile main frame including atransverse portion; a transversely elongated header carrying cropharvesting elements and disposed generally forwardly of the transversemain frame portion; a pair of upper link means pivotally connected attheir rearward ends to the transverse portion of the main frame and attheir forward ends to the header; a pair of lower link means; firsttransverse pivot means connecting the forward ends of the lower links tothe header; means pivotally connecting the rearward ends of the lowerlinks to the main frame, and including second transverse pivot means;means pivotally connecting the rearward ends of the lower links to themain frame, and including second transverse pivot means; hydrauliccylinder means having one end operatively connected to the main frame;connecting means operatively connecting the other end of the cylindermeans to the header so that actuation of the cylinder raises and lowersthe header relative to the main frame; and stop means operativelyassociated with the lower link means for limiting the swinging of thelower link means about the first pivot means after a predeterminedamount of upward movement of the header relative to the main frame.

19. The invention defined in claim 18 wherein the connecting meansconnecting the cylinder means to the header includes said lower linkmeans.

20. The invention defined in claim 18 wherein the means connecting therearward ends of the lower links 'to the main frame includes a pair ofrearwardly extending wheel arms pivotally connected to the transverseportion of the main frame adjacent their forward ends for swinging in avertical arc relative to the main frame and having ground-engagingwheels adjacent their rearward ends, the second transverse pivot meansconnecting the lower links to the wheel arms.

21. The invention defined in claim 20 wherein the connecting meansconnecting the hydraulic cylinder means to the header includes saidwheel arms and said lower links, so that extension of thecylinder meansswings the wheel arms downwardly relative to the main frame to raise thelatter, the downward movement of the wheel arms causing the lower linksto swing about said first pivot means until'the lower link engages thestop means, additional extension of the cylinder means raising theheader about the wheel arm pivot connections to the main frame.

1. A crop harvesting machine comprising: a longitudinal frame portionadapted at its forward end for attachment to a draft vehicle; atransverse frame portion rigidly fixed at one end to the rearward end ofsaid longitudinal frame portion; a pair of transversely spaced uprightframe members rigidly fixed at their lower ends to said transverse frameportion; a pair of longitudinally extending, transversely spaced wheelarm means pivotally connected at their forward ends to said transverseframe portion for vertical swinging movement, each of said wheel armmeans having a ground-engaging wheel rotatably supported on its rearwardend; extensible and retractable means interconnecting said upright framemembers and said wheel arm means for vertically swinging the latter andthereby raising and lowering the frame portions relative to the ground;a header subframe carrying harvesting elements thereon, said headerbeing disposed generally above and forwardly of said transverse frameportion and including a portion extending rearwardly between saidupright frame members; lower, longitudinally extending link meansinterconnecting said wheel arm means and a lower portion of said header;upper, longitudinally extending link means interconnecting the upper endportions of said upright frame members and an upper portion of saidheader; and resilient means acting between said transverse frame portionand said header for urging the latter upwardly relative to the former.2. The invention defined in claim 1 wherein said resilient meanscomprises spring means interconnecting said upper link means and saidheader.
 3. The invention defined in claim 1 wherein said resilient meanscomprises spring means interconnecting the upper end portions of saidupright frame members and said header.
 4. The invention defined in claim1 including stop means on said header engageable with one of said linkmeans to limit the relative movement between said one link means andsaid header as the wheel arm means are swung downwardly to raise theframe portions relative to the ground.
 5. The invention defined in claim4 wherein said stop means are engageable with said lower link means tolimit the upward movement of the header relative to the lower link meansas the wheel arm means are swung downwardly.
 6. The invention defined inclaim 1 wherein said lower link means extend beneath the transverseframe portion.
 7. The invention defined in claim 6 wherein the upperside of said lower link means is engageable with the lower side of saidtransverse frame portion to limit the upward movement of said headerrelative to said transverse frame portion.
 8. The invention defined inclaim 1 wherein the lower side of said header is engageable with theupper side of said transverse frame portion to limit the downwardmovement of said header relative to said transverse frame portion. 9.The invention defined in claim 1 including an upper and lower pair ofcooperating, crop conditioning rolls mounted on said header, one of saidrolls being mounted on said header for movement toward and away from theother of said rolls, and whereIn said resilient means acts between saidtransverse frame portion and said one conditioning roll tosimultaneously urge the header upwardly relative to the transverse frameportion and urge said one conditioning roll toward said otherconditioning roll.
 10. The invention defined in claim 9 including armmeans mounting the upper of said crop conditioning rolls on said headerfor vertical swinging movement toward and away from the lower of saidrolls, bell crank means mounted on said header, and link meansinterconnecting one arm of said bell crank means with said upper rollmounting arm means; and wherein said resilient means acts between theother arm of said bell crank means and said transverse frame portion.11. The invention defined in claim 10 wherein said resilient meanscomprises spring means interconnecting the other arm of said bell crankmeans and said upper link means.
 12. The invention defined in claim 10wherein said resilient means comprises spring means interconnecting theother arm of said bell crank means and the upper end portions of saidupright frame members.
 13. The invention defined in claim 1 wherein saidground-engaging wheels are disposed inwardly of said upright framemembers and beneath the portion of said header extending rearwardlybetween said upright frame members.
 14. A pull-type crop harvestingmachine comprising: a longitudinal frame portion adapted at its forwardend for attachment to a draft vehicle; a transverse frame portionrigidly fixed at its left end to the rearward end of said longitudinalframe portion; right and left, transversely spaced upright frame membersrigidly fixed at their lower ends to the respective end portions of thetransverse frame portion; right and left, transversely spaced wheel armspivotally connected to the transverse frame portion adjacent to thelower ends of the respective upright frame members, each of said wheelarms extending rearwardly from its pivotal connection with thetransverse frame portion and having a ground-engaging wheel rotatablysupported on its rearward end; right and left, extensible andretractable means interconnecting the respective upright frame memberand wheel arm to vertically swing the latter and thereby raise and lowerthe frame portions relative to the ground; a header subframe carryingharvesting elements thereon, said header being disposed generally aboveand forwardly of said transverse frame portion and including a portionextending rearwardly between said upright frame members; right and left,longitudinally extending lower links pivotally connected at theirrearward ends to intermediate portions of the respective wheel arms,said lower links extending forwardly therefrom beneath said transverseframe portion and being pivotally connected at their forward ends tolower portions of said header; right and left, longitudinally extendingupper links pivotally connected at their rearward ends to the upper endsof the respective upright frame members and at their forward ends toupper portions of said header; and right and left, vertically extendingspring means connected at their upper ends to the upper ends of therespective upright frame members and at their lower ends to the header.15. The invention defined in claim 14 wherein said ground-engagingwheels are disposed inwardly from said upright frame members and saidspring means are disposed outwardly from said upright frame members. 16.The invention defined in claim 14 wherein said upright frame members areformed of rearwardly opening, U-shaped channels, and wherein saidextensible and retractable means comprise hydraulic cylinders disposedbetween the walls of said channels.
 17. A pull-type crop harvestingmachine comprising: a longitudinal frame portion adapted at its forwardend for attachment to a draft vehicle; a transverse frame portionrigidly fixed at its left end to the rearward end of said longitudinalframe portion; right and left, transversely spaced upright frame membersrigidly fixed at theIr lower ends to the respective end portions of thetransverse frame portion; right and left, transversely spaced wheel armspivotally connected to the transverse frame portion adjacent to thelower ends of the respective upright frame members, each of said wheelarms extending rearwardly from its pivotal connection with thetransverse frame portion and having a ground-engaging wheel rotatablysupported on its rearward end; right and left, extensible andretractable means interconnecting the respective upright frame memberand wheel arm to vertically swing the latter and thereby raise and lowerthe frame portions relative to the ground; a header subframe carryingharvesting elements thereon, said header being disposed generally aboveand forwardly of said transverse frame portion and including a portionextending rearwardly between said upright frame members; right and left,longitudinally extending lower links pivotally connected at theirrearward ends to intermediate portions of the respective wheel arms,said lower links extending forwardly therefrom beneath said transverseframe portion and being pivotally connected at their forward ends tolower portions of said header; right and left, longitudinally extendingupper links pivotally connected at their rearward ends to the upper endsof the respective upright frame members and at their forward ends toupper portions of said header; and right and left, vertically extendingspring means connected at their upper ends to intermediate portions ofthe respective upper links and at their lower ends to the header.
 18. Aharvesting machine comprising: a mobile main frame including atransverse portion; a transversely elongated header carrying cropharvesting elements and disposed generally forwardly of the transversemain frame portion; a pair of upper link means pivotally connected attheir rearward ends to the transverse portion of the main frame and attheir forward ends to the header; a pair of lower link means; firsttransverse pivot means connecting the forward ends of the lower links tothe header; means pivotally connecting the rearward ends of the lowerlinks to the main frame, and including second transverse pivot means;means pivotally connecting the rearward ends of the lower links to themain frame, and including second transverse pivot means; hydrauliccylinder means having one end operatively connected to the main frame;connecting means operatively connecting the other end of the cylindermeans to the header so that actuation of the cylinder raises and lowersthe header relative to the main frame; and stop means operativelyassociated with the lower link means for limiting the swinging of thelower link means about the first pivot means after a predeterminedamount of upward movement of the header relative to the main frame. 19.The invention defined in claim 18 wherein the connecting meansconnecting the cylinder means to the header includes said lower linkmeans.
 20. The invention defined in claim 18 wherein the meansconnecting the rearward ends of the lower links to the main frameincludes a pair of rearwardly extending wheel arms pivotally connectedto the transverse portion of the main frame adjacent their forward endsfor swinging in a vertical arc relative to the main frame and havingground-engaging wheels adjacent their rearward ends, the secondtransverse pivot means connecting the lower links to the wheel arms. 21.The invention defined in claim 20 wherein the connecting meansconnecting the hydraulic cylinder means to the header includes saidwheel arms and said lower links, so that extension of the cylinder meansswings the wheel arms downwardly relative to the main frame to raise thelatter, the downward movement of the wheel arms causing the lower linksto swing about said first pivot means until the lower link engages thestop means, additional extension of the cylinder means raising theheader about the wheel arm pivot connections to the main frame.